A complex service call on an urban rooftop in Montreal
At AirGreen , we are regularly called upon for technical interventions on HVAC installations in urban areas. One of our recent missions took place in the Côte-des-Neiges–Notre-Dame-de-Grâce district of Montreal, where a commercial client contacted us regarding a problem with a Midea heat pump installed on the flat roof of their building.
The unit, a Midea MultiZone wall-mounted system , supplied power to several offices inside the building. The initial call reported a lack of heating and cooling in several zones, accompanied by an intermittent error message on the interior display.
Diagnosis: Interrupted communication between units
Upon our arrival, our technicians immediately noticed that the outdoor heat pump was not responding properly to the signals sent by the wall-mounted heads. After a visual inspection, several clues guided our diagnosis:
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The electrical connections at the terminal block were slightly corroded, a result of prolonged exposure to outdoor conditions.
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The communications cable exhibited unstable voltage, possibly caused by a partially severed wire in the insulating sheath.
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The drain line was also showing signs of wear, causing moisture to seep into the lower compartment.
To confirm our assumptions, we connected our electronic diagnostic tools and ran a series of tests on the communication circuit and voltage values . The verdict: the main electronic board (PCB) of the outdoor unit was no longer receiving signals from the indoor units correctly.
Repair: replacement of the control board and rewiring
The solution chosen was the complete replacement of the Midea heat pump's PCB . This delicate operation, carried out on the flat roof, required:
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Safe power cut-off and complete disconnection of the electronic module.
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Cleaning and preparing the electrical compartment , in order to eliminate all traces of humidity and accumulated dust.
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Replacement of the communication cable , made with a high quality shielded cable to avoid any electromagnetic interference.
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Complete check of the refrigeration and electrical connections , as well as the pressure switch to ensure the system is properly balanced.
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A complete functional test of the indoor units to confirm communication recovery and system stability.
Our technicians also added an anti-corrosion treatment to the new connections to extend the life of the system, given its direct exposure to the elements.
Results: restored comfort and renewed efficiency
After the replacement and final checks, the Midea heat pump resumed normal operation. Performance tests showed excellent thermal response in all areas of the building, with stable performance even in low-temperature heating mode.
The client, relieved to find comfort in their premises, particularly appreciated our rigorous approach and our attention to detail, in particular the orderly routing of the refrigeration and electrical cables for easier future maintenance.
Lessons Learned and AirGreen Tips
This type of intervention on a Montreal flat roof perfectly illustrates the unique challenges our technicians face:
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Prolonged exposure to the elements (rain, snow, wind) requires regular maintenance of electrical connections.
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Vibrations and thermal expansion can, over time, damage communication cables.
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Electronic cards must be protected by suitable sheaths and fixings to prevent moisture infiltration.
At AirGreen , we recommend that all commercial building owners with rooftop heat pumps schedule a comprehensive annual inspection before each heating and cooling season. This preventative maintenance helps prevent unplanned shutdowns and maintains the system's energy performance.
AirGreen: your HVAC expert in Montreal
Whether in Montreal , Laval , Longueuil , on the North Shore or the South Shore , our team stands out for its technical expertise and in-depth knowledge of Midea , Gree , Fujitsu , Sharp systems, and many others. Every service call is handled with the same rigor: an accurate diagnosis , lasting repairs and a commitment to performance and reliability .
Is your heat pump showing signs of weakness or an error message?
Contact AirGreen today for fast, professional service on any type of residential or commercial HVAC equipment.